Sunday, March 2, 2008

If I had a hammer or a molten salt reactor

I subscribe to a google alert for capacitors technology. My theory is that ultra-capacitors will play a major in the post carbon world. An alert that slide into my yahoo mailbox this morning lead me to the following observation:

Suppose that a classically educated, but sheltered, engineer is asked to devise a procedure to drive nails into wood. If he or she is unaware of the concept of the hammer, the engineer is likely to develop something that looks like a modern press. The device might be built so that it precisely aligns a nail normal to the piece of wood and has an actuator that moves at a controlled displacement rate (possibly with high force) and drives the nail slowly into the board.

Other engineers might applaud this approach as it offers much control and precision. By way of added improvements, the engineering community would work on issues such as the stability and buckling of the nail as well as the challenge of making a truly portable nail driver. Over time, others would improve on this approach. Standards would be developed and the viability of many companies might become dependent on its continuation.

Now imagine another engineer suggesting that this common but somewhat elegant process could be replaced by simply banging on the head of the nail to drive it into the wood. While this has many advantages in terms of simplicity, cost, stability of the nail and portability, it might encounter some resistance as it appears some control over the process is lost and there might be a substantial learning curve in developing good hammers and the skills needed to wield them properly.

Fortunately the hammer was developed long before conventional engineering practices!

In some sense this analogy parallels the state of sheet metal forming technology today. Forming typically is accomplished with the motion of massive matched tools with precise control of static forces and slow displacement rates. In effect, we now are suggesting that much might be accomplished by hurling chunks of metal into dies.

What we are dealing with is a natural human tendency to follow accepted patterns of thinking and acting, rather than explore the possibility that other patterns might be preferable. Long ago I discovered that people were most like to change when they had no choice. The young are more ammenable to change because they have not yet patterned their central nervous system with old ways of thinking and acting. Foreigners and outsiders are more likely to pick up new ideas of thinking and acting, to take advantage of new opportunities, than people who can point to long traditions in the old ways.

The MSR technology sounds promising (and depressing, to think that TMI and Chernobyl might have been avoided if this technology would have become dominant but due to apparently nontechnical reasons this never happened). - Tap-Sa

Well perhaps it would be better to say that TMI and Chernobyl would be impossible with MSR technology and leave it at that. Last month, I think that I demonstrated that MSR technology was rejected by the United States political establishments for irrational reasons. Consider the MSR as the hammer, and the LWR as the press. It is not that the idea of the Molten Salt Reactor was unknown, however. It was just that the LWR looked to the Navy like the tool that it needed. The Air Force had the crazy idea of using molten salt reactors to provide nuclear power for flight, so the molten salt reactor got off on the wrong foot by being associated with a a bad idea. The Navy thought in terms of boilders, turbines and electricity. Much of Hyman Rickover's naval career, was based on his understanding of electrical generating systems. The Light Water Reactor fit into the Navy's propulsion system because it generated the super heated water that when turned to steam would run ships efficiently. For the Navy the LWR look like a great tool, because ships could travel for years without refueling, using light water reactor technology. As long as it kept the ships running and not create big problems for the Navy, the LWR was a satisfactory tool.The Navy had patterned its shipboard propulsion systems after land based electrical generation technology. As a consequence any advance in Naval propulsion technology had the potential to feed back into the civilian power industry. This is exactly what happened.

There were problems with light water reactor technology. Some problems that could be fixed. Some which could not be fized. The basic problem is that a light water reactor is not a very efficient way of extracting the potential energy present in nuclear fuel. The CANDU reactor which uses heavy water is a somewhat better tool, but still extracts only a tiny fraction of the energy present in nuclear fuel.

The big problem emerged as soon a LWR technology was applied to civilian power use. A whole lot of what went into the reactor as nuclear fuel came out as "nuclear waste." This problem is greatly magnified because of the inefficiency of fuel use in light water technology. What appears to the naval propulsion engineer, or to the engineers for industries that produced civilian electrical technologies, as a highly efficient fuel process, struck nuclear scientist as messy and inefficient. The messiness results in the unmanageability of slightly used nuclear fuel. The sort of stuff that comes out of a LWR.

Alvin Weinberg, who patented the Light Water Reactor, knew full well its limitations. Weinberg had a hammer. It was called the Molten Salt Reactor, and it potentially had none of the LWR's limitations. But the advocates of the LWR technology said, "You can never get the thing to work." And they made sure that no chance would ever be given to those who wished to prove them wrong.